gistfile1.rb

# XmlObjectParser by Dan Lynn

xml_str = <<XMLEND
<inventory title="OmniCorp Store #45x10^3">
  <section name="health">
    <item upc="123456789" stock="12">
      <name>Invisibility Cream</name>
      <price>14.50</price>
      <description>Makes you invisible</description>
    </item>
    <item upc="445322344" stock="18">
      <name>Levitation Salve</name>
      <price>23.99</price>
      <description>Levitate yourself for up to 3 hours per application</description>
    </item>
  </section>
  <section name="food">
    <item upc="485672034" stock="653">
      <name>Blork and Freen Instameal</name>
      <price>4.95</price>
      <description>A tasty meal in a tablet; just add water</description>
    </item>
    <item upc="132957764" stock="44">
      <name>Grob winglets</name>
      <price>3.56</price>
      <description>Tender winglets of Grob. Just add water</description>
    </item>
  </section>
  <to_s>a string</to_s>
</inventory>
XMLEND


# REXML Tutorial = http://www.germane-software.com/software/rexml/docs/tutorial.html



require 'rexml/document'


class XmlObjectParser
  
  retained_methods = %w(__send__ __id__ send class inspect instance_eval instance_variables)
  instance_methods.each { |m| 
    undef_method(m) unless retained_methods.include?(m)
  }
  
  def initialize(node, parent_node=nil)
    @node = node
    @node = REXML::Document.new(node) if node.is_a?(String)
    @parent_node = parent_node
  end
  
  def method_missing(method, *args)
    child_node = @node.elements[method.to_s] || @node.attributes[method.to_s]
    return child_node if child_node.is_a?(String)
    return child_node.text if !child_node.has_elements?
    return XmlObjectParser.new(child_node, @node)
  end
  
  def [](*args)
    return XmlObjectParser.new(@parent_node.elements[*args], @parent_node) if args[0].is_a?(Fixnum)
    return XmlObjectParser.new(@node.elements[*args], @node)
  end
end



# my simple version
xml = XmlObjectParser.new(xml_str)
puts xml.inventory.section.name
puts xml.inventory.section.item.stock
puts xml.inventory.section[2].inspect
puts xml.inventory["section/item[@stock='44']"].upc
puts xml.inventory.section.item.name
puts xml.inventory.to_s # note that Object's to_s method has been undefined

# the long REXML version
puts "\n"
doc = REXML::Document.new(xml_str)
puts doc.elements['inventory'].elements['section'].attributes['name']
puts doc.elements['inventory'].elements['section'].elements['item'].attributes['stock']
puts doc.elements['inventory'].elements[2].attributes['name']
puts doc.elements['inventory'].elements["section/item[@stock='44']"].attributes["upc"]
puts doc.elements['inventory'].elements['section'].elements['item'].elements['name'].text
puts doc.elements['inventory'].elements['to_s'].text


# SAMPLE OUTPUT =================
# >> health
# >> 12
# >> #<XmlObjectParser:0x48778 @parent_node=<inventory title='OmniCorp Store #45x10^3'> ... </>, @node=<section name='food'> ... </>>
# >> 132957764
# >> Invisibility Cream
# >> a string
# >> 
# >> health
# >> 12
# >> food
# >> 132957764
# >> Invisibility Cream
# >> a string